


The second Blood Traitor

by Glade



Category: Harry Potter - J. K. Rowling
Genre: Anxiety, F/M, First War with Voldemort, M/M, Multi, The Potters Live
Language: English
Status: In-Progress
Published: 2017-04-30
Updated: 2018-06-11
Packaged: 2018-10-25 16:58:27
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 4
Words: 3,623
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/10768536
Author URL: https://archiveofourown.org/users/Glade/pseuds/Glade
Summary: What if, after nearly dying at the cave, Regulus gets to Dumbledore and assists in the War? The spy Wormtail gets outed before he becomes the Secret Keeper, and Dumbledore learns about the Horcruxes much earlier.





	1. (Introduction) The Prophecy

**Author's Note:**

  * For [WiledWolves](https://archiveofourown.org/users/WiledWolves/gifts).



The one with the knowledge to defeat the Dark Lord approaches,  
He will save the one born to those who have thrice defied him, born as the seventh moon dies  
And the Dark Lord has marked him as his servant, but he has power the Dark Lord understands not  
And either must die by the hand of the other for neither wishes to see a world where the other survives  
the one with the knowledge to defeat the Dark Lord approaches...


	2. Chapter 1

**Summary for the Chapter:**

> Regulus arrives, but what does he want with Dumbledore? And is Wormtail right to be so cautious about a Death Eater under the Potters roof?

The next thing Regulus felt was the unpleasant squelch of house-elf apparition. He tried to spare a thought of annoyance for the meddling creature, but his entire focus was on coughing up the lung-full of water he had breathed in as he had been dragged to his watery grave by the inferi.

The four marauders and Lily were having dinner when Kreacher and Regulus appeared in the room, Kreacher standing protectively in front of Regulus. There was an almost comical heartbeat of total stillness as everyone tried to take in what’s happening, before all hell broke loose.

Wormtail was the first to react. Drawing his want almost Auror-fast, he snapped out “Sectumsempra!” Kreacher batted the spell away, glaring at him.

“You shall not harm Regulus Black!” the house elf squeaked.

“Dumbledore!” Regulus rasped out, having finally finished coughing up the water from his lungs. “I need to talk to Dumbledore!”

Wormtail looked ready to try another curse, but James took over before he had a chance to think of some way to get around Kreacher’s protectiveness. He (with permission from Regulus and Kreacher) cast a nifty Aurors spell to block Regulus’s ability to cast spells, except in a life-or-death situation, and confiscated his wand.

Approximately half a second later, Sirius tore himself away from Remus and dropped to his knees in front of Regulus. He reached out a hesitant hand to Regulus’s shoulder, then grabbed Reg in a fierce embrace which caused Regulus to cough some more.

“But James,” Peter hissed, grabbing his arm as James went into the kitchen to get another plate and some cutlery, “he’s a Death Eater.”

James put the plate down and turned to face Peter fully. “He’s also completely harmless now, and he wants to talk to Dumbledore. I don’t know what he wants, but it doesn’t hurt to feed him and help him tonight, and Dumbledore can decide what to do with him. We’re not winning this war, Peter; we can’t afford to turn away potential allies.”

Wormtail bit his lip and glanced back at Sirius, who was by now crying on Regulus’s shoulder. “I suppose. But do you really think it would be a good idea to keep him here with Sirius? I mean, with all the past history between them...” he trailed away nervously.

Prongs glanced over at the pair of them as well. “Peter, we’re in the middle of a war. Any of us could be dead soon. I’m not going to separate the two of them now they’ve found each other.” James paused, and looked at Peter, frowning slightly. “What’re you worried about?” he asked.

Wormtail started, then relaxed, giggling nervously. “Never could hide anything from you, Prongs. Just that...Sirius has already been hurt so much by Regulus and all that. What if this time, he doesn’t recover?”

“He won’t.” James replied immediately. “He’s got Moony, and he’s got us. And I very much doubt that any plan of You-Know-Who involves sending Regulus here specially to hurt Padfoot, okay? Let’s get Regulus some food and dry clothes, and then we can send Dumbledore a message and see what he says about it all.” He pulled free of Peter and took the crockery into the other room.

Peter scowled and rubbed his left arm nervously before following James back into the other room.

Regulus had stripped down to his underwear and Lily was carefully applying a burn plaster to an angry red stripe across Regulus’s too-prominent ribs. Remus was standing next to her with a towel and a bruise potion.

Sirius was still holding Regulus’s hand, barking with laughter at something Regulus had said. This close together, the family resemblance was obvious. The same black hair and grey eyes. The same cheekbones, although Sirius’s were softer with regular good food. Even their smiles matched, revealing dimples in their left cheeks. Sirius’s Auror training had given him more muscle, obvious even through the bulky robes he was wearing, and Regulus had an extra inch, but they were the only obvious differences.

Lily finished what she was doing and stepped back. “Just give that a few minutes to set, then it can come off tomorrow morning.” she said, forestalling Remus who had moved to give Reg the towel. He handed Reg the potion instead, which Reg downed in three gagging swallows.

“Trying to poison me, Lupin?” Regulus asked, scowling. “That tasted foul!”

Sirius laughed again. “Blame James. He’s managed to make the potion more effective, but the taste is so much worse.”

James glanced up at the sound of his name, just in time for Regulus to salute him sarcastically. James grinned, and finished putting an extra space at the table for Regulus.

“So,” James drawled, running his fingers through his hair, “what do you want us to call you? I doubt, since you’re here, that you’re still throwing your lot in with your parents, so I’m assuming not Black.”

“I...” Regulus started inelegantly, then paused, glancing at Sirius for reassurance. Sirius grinned back at him and nodded encouragingly. “Well, yeah, not that, I guess. And Regulus seems a bit stuffy these days, how about Reg?” Sirius grinned at him, delighted.

“Sounds great,” James said. “Then I’m James, Remus, Peter and Lily.” He pointed to each of them in turn, and Reg nodded to each of them.

Dinner that night was a stilted affair. No-one knew quite what to say to each other, and after a few attempts by Peter they all fell silent. Sirius could hardly eat properly, all his attention fixed on his long-lost brother, and Reg was nearly falling asleep at the table, even while he finished thirds.

Eventually even Reg couldn’t eat any more, and Lily sent the plates to be washed up with a tap of her wand. “Technically, we’re not supposed to use too much magic around here,” she explained to Reg as she led him upstairs to the guest bedroom, “since we’re not sure what can and can’t be traced. But we figure the odd bit is alright. And there are plenty of witches and wizards staying out of the war, You Know Who doesn’t bother going after every little bit of magic used, just large concentrations.”

Reg nodded mutely, barely able to keep his eyes open as he followed Lily into the guest bedroom. He was asleep before he managed to take his shoes off.


	3. Chapter 2

**Summary for the Chapter:**

> Reg tells Dumbledore all that he knows

**Notes for the Chapter:**

> Oh my actual gosh I'm so sorry Sirius, it totally isn't your fault...

The next day Dumbledore summoned Reg, James and Peter (Remus and Sirius were off on an Order mission, much to Sirius’s disgust and annoyance, but they would be along later) to a little pub in a quiet, forgettable village. The three of them apparated all around the country before finally landing at their destination just as dusk was falling. They entered the pub, James ducking under the low door frame first, fingers clenched around his and Reg’s wands in his jacket pocket. A quick glance around the pub showed a normal assortment of old ‘regulars’ and a cycling group in one corner, so the three of them settled in an out of the way corner which had views to both the doors out as well as the bar.

A few minutes later Dumbledore arrived, wearing a rather (for him) toned down suit with a chevron pattern picked out in rainbow colours. He spotted the others, paused to talk briefly to the bartender and give her some cash, then weaved his way to the table they were sat at.

Dumbledore sat own opposite them, his back to the room in general. He waved his wand, subtly hidden in a sleeve in a discrete patten and the background noise of everyone talking and music died down.

“Now, my boy. What can we do for you?” Dumbledore asked Reg, blue eyes piercing.

In answer Reg pulled a necklace from under his clothes and put it on the table in front of them all. The green emeralds glittered in the light. “Don’t touch it!” he warned quickly as James moved to pick it up. “I don’t know what other protections are on it.”

Peter was white, staring at the locket as if he heard something from it.

“What is it?” Dumbledore asked, seemingly unconcerned about the proximity of a presumably very dark and dangerous object.

Reg sighed, running a hand through his short hair. “Part of Voldemort’s soul.” Everyone, including Dumbledore, stared at him. “Have any of you heard of a horcrux?”

Dumbledore whitened. “I’ve heard of them, but never suspected...you are sure?”

Reg nodded, mouth set into a grim line. “ _He_ said something that made me suspect, and then I managed to sneak into his private library. There was a book open about what can destroy them, so I did some more digging of my own. This was hidden in a cave near where he grew up, guarded by magic and inferi and some sort of sophisticated poison. I didn’t expect to get out alive, but house elves can be rather stubborn.”

Dumbledore twinkled his eyes at them all, including James and Peter who didn’t have a clue what was being discussed, but instead concentrating on the other patrons of the pub. “I’m afraid that Tom will always know nothing about what he considers to be lesser sorts of magic, that of house elves, children’s tales, love and innocence. I am glad to see that one Slytherin was not so blind.”

Reg blinked at him, clearly a bit confused, before recovering and carrying on. “Err, right. Well, a couple of things can destroy them. The main idea seems to be that you have to destroy the container beyond repair, but that’s complicated by the horcrux being magically protected too. Fiendfyre definitely works according to the books I saw, but they couldn’t decide about the killing curse. One book also mentioned the possibility of some of the darkest poisons, but it was only a hypothetical.

“However, you’ve got a bigger problem than destroying this horcrux.”

“He made more?” Guessed James, who had caught up enough on the conversation to work out that horcruxes were bad, even if he didn’t know what exactly was bad about them.

“Oh sweet Salazar I hope not.” Reg replied, his normally pallid features paling more at the suggestion that there were more. “He wouldn’t, surely?” He glanced at Dumbledore, who was looking alarmed and saddened.

“When Tom came to me, asking for the Defence against the Dark Arts position when he finished school, he mentioned pushing the boundaries of magic further than anyone else. I am now wondering if he did, indeed, create multiple horcruxes. But I suspect that you meant something else, my boy?”

Reg nodded grimly. “There’s a spy in the Order. I don’t know who he is, but everyone whispers about him being one of ‘the four’, whatever that means.” James whitened, and glanced at Dumbledore.

“I see,” Dumbledore said slowly, glancing down at his hands momentarily, then back up at the group. “James-” Before he could finish his sentence, Remus and Sirius entered the pub, laughing. They spotted the quartet and headed over, grinning broadly and dripping wet. They were in good spirits, laughing and joking with each other, but when they passed the privacy barrier Dumbledore had erected and they saw the serious looks on everyone’s faces, they calmed down, hands dropping to wand pockets.

“What’s going on?” Remus asked, dropping into an empty stool and reaching curiously for the locket.

“Don’t!” came the call from 4 voices at once, and he sat back, leaving the locket untouched.

Dumbledore cleared his throat, and everyone looked at him. “Reg has brought us some very troubling news, gentlemen. I am immeasurably sad to have to insist on this, but please could you- not you Reg, I assume you’re marked?” Dumbledore paused while Reg nodded before continuing- “please show me all your left arms.”

Remus and Sirius stared at Dumbledore as though he’d gone completely insane. James was the only one who complied, pushing up his sleeve to reveal a completely bare arm.

“Gentlemen?” he prompted after a few seconds when it became clear that the others were still frozen in shock.

“Now Headmaster, really,” protested James, “surely we can’t be the only contenders for the spy. I trust all three of my friends here. None of us would ever spy for Vol-Voldemort.” Peter flinched at the name, causing James to turn to him in annoyance “Peter will you please just...” he trailed away at the look on Peter’s face. “No, tell me you didn’t,” he whispered, horrified.

Sirius and Remus had completely lost their good mood from an Order mission well executed and were also staring at Peter in horror.

Reg felt the tension around him and froze up, expecting the shouting to start at any second.

Dumbledore took about one eye-blink to take this all in and act before anyone else could draw attention to themselves. He wandlessly summoned everyone else’s wand to himself and put the four marauders under a general body bind curse before they had the excellent idea to fight it out the muggle way.

“Gentlemen, while I completely understand your anger, need I point out that we are in a muggle pub and we do not want to draw attention to ourselves. Now then, I suggest the following plan of action. We will leave this pub calmly- yes Peter that includes you I’m afraid. I have some questions which I will require answers to-, and then we will apparate to Hogwarts, where you can have the shouting match I rather fancy you are all working yourselves up to. Then you four-” Dumbledore paused to nod politely at Reg who was still sitting there, braced for the shouting to come- “will go home and leave Peter and I to have a _discussion_.” There was no doubt in anyone’s mind that the discussion would be unpleasant at best.

* * *

“We trusted you!” James howled at Peter as soon as he was released from the body bind. He clenched his hands, longing to punch the face of his one-time friend, but Dumbledore’s magic prevented him from moving. This was to be a shouting match only.

“You don’t understand!” whined Peter, licking his lips nervously, “He’s too powerful. He threatened me...” he broke off, shuddering in remembered pain.

“Then you should’ve died! Died with your head held high like the Gryffindor you always claimed to be!” James turned away, disgusted. He looked out over the Hogwarts grounds, remembering all their crazy adventures. He felt sick as he remembered all the things they had done together as a group of four, all the pranks they’d pulled.

“But...why?” asked Sirius, also remembering all their pranks. “What did we do that was so horrible that made you think _that-”_ he waved inaccurately at Peter’s arm- “was the best available option to you?” He tried to carry on, but the tears started. The old fear resurfaced, the fear that he would one day say something- do something so unutterably foul that his friends would turn against him and he wouldn’t even understand why.

At the first tear, James turned and instantly forgot his rage at Pettigrew in favour of hugging Sirius tightly, murmuring reassurances that it wasn’t his fault into Sirius’s hair. Remus saw the tears and saw red. Using his anger, he forcibly broke the enchantments Dumbledore had put in place to keep Pettigrew alive and unharmed and punched the snivelling coward in the face. Then he got himself under some sort of control and turned away. While Sirius was worth it even if Pettigrew wasn’t, there were better ways to help Sirius deal with this, and Remus hurried back over to Sirius to add himself to the group hug which Reg had also been pulled into by James.

Dumbledore gave them a moment before clearing his throat. They slowly untangled themselves, Remus and James keeping a solid grip on Sirius. “I am so very sorry for all this,” the old man said slowly, looking over all of them. “Here is a portkey home, and of course all your wands back.” Mutely, they accepted the wands and the portkey and vanished from the grounds.

“And now, Pettigrew,” Dumbledore said, and he no longer looked like an old doddering wizard but an angry warrior, “let’s have a little chat shall we?”


	4. Curse him off the map

**Summary for the Chapter:**

> Lily comes home. Dinner is eaten. Sirius gets angry. Reg freaks.

**Notes for the Chapter:**

> CW: Reg has a fight/flight reaction to Sirius getting angry.

ames strode through the front door, his face thunderous. Remus and Sirius followed him, Remus almost as angry but holding Sirius tightly, who was withdrawn and curled into himself, tear tracks still visible on his face. Finally, Reg brought up the rear, not sharing in their grief and feeling unsure what he should be doing.

Remus pulled an unresisting Sirius onto his lap, alternating between murmuring something quietly into his ears and pulling back to check the effect his words were having on Sirius. James flicked his wand over his shoulder and Reg flinched, but the spell was aimed at a large crystal decanter, which poured its contents into three matching brandy balloons. James strode over angrily to collect them, causing Reg to scuttle out of the way, eyes wide and nervous.

He left two of the balloons on the table next to Sirius and Remus and sat on the other sofa, hands cradling the balloon as he stared out at nothing.

After a few minutes of silence, Reg uncurled from where he was standing near the door and sat down at the dining table, back ramrod straight as he kept his eyes fixed on James. He was still sitting like that when Lily came home in a burst of green floo powder and a positive, upbeat smile which dropped as soon as she saw everyone.

“What’s wrong?” she asked, dropping her bag haphazardly on the floor and heading over to sit next to James. “Where’s Peter?”

At the rat’s name, James’s face darkened further and he stood up abruptly, leaving Lily sat alone. Reg recovered from where he had frozen at James’s sudden move and stood up, walking gracefully across the room to sit in the vacant seat next to Lily. In hushed tones, he quickly explained what had happened, eyes flitting between James, Remus and Sirius, who was finally drinking with shaking hands, Remus helping hold the brandy balloon. When he finished explaining the final arguement with Peter, Lily stared at him horrified for a second, before leaping to her feet and rushing to James’s side to hug him tightly. Even with everything else going on, Reg was hit with a faceful of Lily’s bright red hair, and it took him a few seconds to get over how vibrant it was.

Reg sat there, watching the other couples comfort each other, and felt the usual feeling of ‘otherness’ creep over him. He wasn’t the same as everyone else, and he felt like he was intruding on an incredibly intimate and private moment. Eventually it got too strong and he left the room, and wandered up to the room he had slept in the night before. He’d had enough nights without dinner that one more wouldn’t hurt.

He was almost dozing when he heard a tentative knock at the door.

“Enter!” he called, and the door opened, revealing Lily’s head.

“Dinner’s been made, if you want to join us. You don’t have to,” she added, realising how formal and insistent her initial offer had sounded. Reg got up and slipped on a robe before following her downstairs.

Dinner that night was a strained affair. Lily tried to start a conversation about her day at work, but Reg was the only one who responded and that quickly petered out.

Near the end, Sirius snapped. “Damn him and his creepy tail. Blast him off the map, he doesn’t deserve to be named on it after this.” Reg froze, adrenaline sending his heart and breathing racing as he remembered the hidden terror of _th_ _at_ night, years ago, when Sirius had finally run away from the Noble and Most Ancient House of Black, and another voice similar to this yelled very similar words. He stared down at the table, ears ringing, clenching his hands under the table where no-one could see them. As his hearing gradually returned, he realised everyone had stopped talking, and he glanced up to see everyone staring at him.

He opened his mouth to snap at them, then remembered his training and shut it again, trying to control his blush. Lily leaned past James to talk to him in a hushed voice. “You don’t need to stay here. We won’t mind if you want to go somewhere else.”

He stared at her like a rabbit caught in the headlights, then nodded shakily and almost ran from the room. As soon as he was back up in his room he curled up on the bed, not sure what he was feeling or how he was supposed to process it.

Sirius half rose from his chair to chase after him, but Remus tugged him back down. “You’re the worst person to go talk to him Pads. It’ll be fine, he doesn’t hate you, and James,” he paused to glance at James, who nodded, “will go talk to him in a bit when he’s had a chance to calm down.” Sirius sat down, hard, then swallowed and nodded.


End file.
